The causal effect of environment on halo mass and concentration

Abstract

Understanding the impact of environment on the formation and evolution of dark matter halos and galaxies is a crucial open problem. Studying statistical correlations in large simulated populations sheds some light on these impacts, but the causal effect of an environment on individual objects is harder to pinpoint. Addressing this, we present a new method for resimulating a single dark matter halo in multiple large-scale environments. In the initial conditions, we 'splice' (i.e. insert) the Lagrangian region of a halo into different Gaussian random fields, while enforcing consistency with the statistical properties of $\Lambda$CDM. Applying this technique, we demonstrate that the mass of halos is primarily determined by the density structure inside their Lagrangian patches, while the halos' concentration is more strongly affected by environment. The splicing approach will also allow us to study, for example, the impact of the cosmic web on accretion processes and galaxy quenching.

6 pages, 5 figures. Accepted 2021 September 10. Received 2021 September 9; in original form 2021 July 7

References in corpus (9)

• Array Programming with NumPy
• Mass and environment as drivers of galaxy evolution in SDSS and zCOSMOS and the origin of the Schechter function
• Astrophysics Source Code Library
• Assembly bias in the clustering of dark matter haloes
• Building Merger Trees from Cosmological N-body Simulations
• How to quench a galaxy
• Efficient Wiener filtering without preconditioning
• Quadratic genetic modifications: a streamlined route to cosmological simulations with controlled merger history
• Angular momentum evolution can be predicted from cosmological initial conditions